I am afraid I am not aware of the best / reputed coaching institutes in that Nagpur. I would suggest you keep in mind the following while selecting the coaching center.

The coaching center should have a permanent faculty. If teachers keep changing, students will find it difficult to have a steady pace in preparations.

The coaching center should not be too far from your residence. Ideally, one must not waste more than one hour in travelling to and fro from the coaching center. It avoids wasting time, and travel fatigue.

Interact with a few past and present students of the coaching before joining. Shiny advertisements and pamphlets, or any other show off seldom means anything. Only those who have already studied in the place can actually tell what the coaching center is really like.

Look within 8-12 kms of your residence for a few coaching centers, and narrow down the possibilities by interacting with students.

We cannot officially endorse any brand here at the moment. Also, all India level coaching institutes (such as Paramount, or Brilliant) that teach for higher level / competitive exams, generally do not impart coaching for UGC NET. I did some research online, and came across a coaching institute named careerendeavour. You can have a look at their website careerendeavour.com. They claim to have taught AIR 4 and 7 of NET / CSIR.

I would suggest you to go to your nearest coaching hubs on any weekend or when you are free, and check out the coaching classes nearby you. Correspondence courses are hardly effective, it is better to join live classes for more effective coaching.

Yes, Everything is available on the internet. Make complete list of topics to study and search for that topic. You will get lot of websites explaining that topic. After that you can solve previous year papers or give mock tests to know how much you have learnt.

Drawback of this method is that you will not find everything at one place. For every topic you need to search.

I have graduated in ECE in 2013 with 74%. I have been perusing my post graduate in VLSI Design, right now in project with an aggregate 73%. Finally I am planning for teaching field after my Ph.D from Kl UNIVERSITY or some other.

Can you suggest me which stream is preferable for me, and how long duration it takes to complete it. Also the Tution Fee details. Can you please send me complete details in Kl University or Nagarjuna University.

The official page for Academic Research Programmes including PhD and M.Phil for KL University is http://www.kluniversity.in/arp.aspx. You can go through the streams they are offering and take up the one you are most inclined towards.

Before deciding, you may do the following.

Read some research papers published in each of these fields. See where your interest lies.

Know about the latest technologies spurred off from the specific field. Do you think you are interested in any one in particular?

Get in touch with professors who have been teaching in one or more of these fields. Take their opinion as well.